Zombie computer viruses that refuse to die
There are many old viruses that are still around and roam the internet continuing infecting computers world wide. They are referred to by security experts as Zombies, since no one can kill them off completely. The most prolific type of Zombie viruses are the worms. Most worms are self-replicating and spread themselves to other victims after cloning themselves.
These malicious programs after infecting vulnerable computers scan the network and internet for other weekly protected machines. Once found the worms clone themselves and self-spreading begins on a new infected host. It only takes a few vulnerable machines and the worms are recreated to continue their Zombie like behaviour.
In 2008, a worm named Conficker was released into the internet infrastructure, seemingly by accident. Conficker continues being the most active virus on the internet, even after 12 years in action. At its peak it is believed to have infected over 15 million Windows PCs. The worm caused so many infections that Microsoft continues to offer a bounty for $250,000 for capturing its creator. Security experts that have reversed engineered the virus managed to reduce infected machines from over 11 million down to one million. After immense effort to squash the virus, Conficker is still finding new victims and haunting its victims to this day.
Conficker might be the most prolific, but it is not alone. There are a wide array of old viruses, malware and worms still active. MyDoom from 2004, SillyFDC from 2007, Virus from 2006 and Sality from 2003 are still making their rounds infecting computers and causing havoc on their victims. Malware code or their derivations can be long-lived on the internet, even DOS (disk operating system) viruses have been known to popup infecting old computers. Viruses and malware are not static, their code can be shared and used in slightly different versions. The basic property of the virus stays the same but slight modifications can produce better results for the hackers.
These trends will continue for some time. New internet of things devices are becoming more popular and they will extend the life of these Zombie viruses. Internet devices that come online such as smart-fridges and smart-owens continue to spread these viruses. These smart devices have the capacity to connect to the internet, but they are not sophisticated enough to run anti-virus software. Users that do not adhere to security experts' advice to create strong passwords and use anti-virus software on their home network, will continue spreading the old viruses. Upgrading your home computers to newer more secure Operating Systems and using anti-virus software, will prevent future spread of old zombie viruses.